Jiangsu's Farmland Carbon Source And Carbon Sink Distribution Characteristics And Influencing Factors Analysis

With the continuous development of society and economy and the excessive activities of human beings, the content of greenhouse gases has been promoted by a large margin. The rising sea level, the melting of glaciers, and the increase in global temperature are all due to the greenhouse effect, which is attributed to the excess emission of carbon in the air. As an important part of land ecosystem, farmland ecosystem cannot be ignored, and the interference by human factors is the most obvious. Therefore, it is of great significance to understand the carbon cycle of farmland ecosystem, as well as the carbon source and carbon sink, which is helpful to the understanding of the process and mechanism. In order to grasp the trend of carbon source and carbon sink of farmland in Jiangsu province from 1995 to 2015 in the past 21 years, and analyze the influencing factors quantitatively. On this basis, it can provide a more reasonable suggestion for Jiangsu province and even the whole country's green development,healthy development and economic development.First of all, a large number of documents are consulted to make a general understanding of the previous research and the current research progress. Then based on previous research, taking Jiangsu Province as an example, estimates of carbon uptake and carbon emissions of the farmland ecosystem in the province, and makes a descriptive statistical analysis of carbon absorption and carbon emissions of different crops in Jiangsu Province. The distribution characteristics of carbon uptake and carbon emissions in different cities in 2014 were analyzed as an example of 13 prefecture level cities in Jiangsu Province. Then, using correlation, regression and VEC model to analyze the influencing factors of farmland's carbon source and carbon sink in Jiangsu Province, and impulse response function was used to analyze the impact of factors on carbon and carbon sinks. Last but not least, according to above analysis,the measures of carbon emission reduction are put forward.The conclusion is drawn by analysis: (1) On the whole,between 1995?2015,Jiangsu province farmland carbon absorption volatility decreased in first 9 years, and increased year by year after 11 years; The trend of grain crops and the overall convergence, while the economic crops showed a decreasing trend, fruit and vegetable crops showed an increasing trend; In the three crops, grain crops are the main carbon source, and the highest contribution rate of rice and wheat.(2) In the 5 carbon emissions,the carbon emissions from the process of "chemical fertilizer application"accounted for the vast majority of them, and the carbon produced by the field irrigation is also larger; From the point of view of carbon emission intensity, the carbon emission intensity of farmland ecosystem in Jiangsu province has an increasing trend; From the point of view of net carbon sink, farmland ecosystem in Jiangsu province is a significant carb- on sink system.(3) In terms of carbon uptake in the 13 cities, Yancheng, Xuzhou, Wuxi, Suqian are lower than other cities; In terms of the carbon emissions of the 13 cities, Yancheng, Xuzhou, Wuxi, Changzhou are lower than other cities; For each city, rice and wheat are the main source of carbon absorption, fertilizer application is the main source of carbon emissions; For carbon sink, the 13 cities are carbon sinks.(4) This paper quantitatively analyzes the influence of agricultural input factors on carbon emissions, crop yield and crop planting structure, and found that the factors and farmland carbon source and carbon sequestration were significant correlation.Based on the above conclusions, the following suggestions are put forward: (1)Reasonable arrangement of crop planting structure, under limited conditions, as far as possible to grow more carbon absorption of crops.(2)Rational planning of agricultural inputs to reduce the intensity of carbon emissions of agricultural inputs, such as reducing the use of chemical fertilizers, pesticides, optimization of farmland irrigation and so on.(3) Farming system rationalization, and constantly optimize the crop planting structure, learn from the high carbon sink cities, thereby enhancing the overall carbon sink function of Jiangsu Province, to achieve the purpose of reducing emissions.(4) The increase of agricultural technology support, to achieve low-carbon and sustainable development of agricultural production, the limited natural resources,the use of technical means to improve crop yield, so as to further improve the farmland ecosystem carbon sequestration capacity.Because the analysis of carbon source and carbon sink is only one part of ecosystem carbon cycle. Taking the technical system as the boundary to research carbon source and sink is a part of the whole farmland ecosystem. This requires us in the future research to focus on the carbon cycle input, output process and movement mechanism.This is beneficial to better grasp the mechanism of carbon in the carbon cycle of farmland ecosystem and improve the estimation accuracy, and in order to provide more practical measures to reduce carbon emissions.